Photographic gelatine layers with plasticizers

ABSTRACT

GELATINE, ESPECIALLY IN PHOTOGRAPHIC GELATING LAYERS, IS PLASTICIZED WITH A WATER-INSOLUBLE, DISPERSED AMIDE, URETHANE OR CARBONATE HAVING THE FORMULA   R1-Z-O-(CH(-R))N-CO-X   AS DEFINED BELOW.

United States Patent Int. Cl. G0sc1/38, 1/02 US. Cl. 96114.4 9 Claims ABSTRACT OF THE DISCLOSURE Gelatine, especially in photographic gelatine layers, is plasticized with a water-insoluble, dispersed amide, urethane or carbonate having the formula Gelatine is the principal binding agent used for the preparation of photographic hydrophilic layers, such as light-sensitive silver halide emulsion layers, protective layers, filter layers or intermediate layers for photographic materials. Hardened gelatine layers are often brittle and friable. The pliability and flexibility is further reduced by drying. Moreover, the resistance to cold is largely dependent on the humidity of the air. As a layer of gelatine on a support dries, strong tensile forces become effective leading to a deformation of the support or increasing the tendency of the material to curl. Gelatine-containing photographic silver halide emulsions which have, for example, been cast onto a triacetyl cellulose support, break when the humidity is low and when there is a sudden bending stress. A support which has a low resistance to splitting is damaged and also breaks.

In order to avoid these disadvantages, plasticisers, for example hygroscopic compounds such as glycerine, are added to the gelatine layers. However, these plasticisers still further increase the dependence of the properties of the gelatine on humidity. The layers usually become even more brittle in air of low relative humidity, since the hygroscopic agents remove the last traces of water from the binding agent of the layer. Other low molecular weight plasticisers, such as diethanol amine and triethanolamine, hydroxyalkyl ethers, water-soluble amides such as formamide and its substitution products, caprolactam derivatives and water-soluble monoamides of dicarboxylic acid, addition products of ethylene oxide with amines and amides Turkey red oil and other sulfonated fatty acids and fats have the disadvantage of being rinsed out of the gelatine layer during photographic processing. Consequently, they are no longer effective after such processing. Furthermore, high molecular weight compounds, such as polymers or copolymers of acrylates, butadiene, isoprene and polyurethanes of very different compositions have been employed as plasticizers for gelatine. Hydroxyethyl cellulose and other cellulose derivatives also lower the brittleness of the gelatine. Many high molecular weight compounds are of limited utility since they reduce the speed of diffusion of the developer.

Others cause a clouding of the layers. Further disadvantages arise with photographic layers containing color couplers which are substituted by long-chained aliphatic radicals and contain sulfonic acid or carboxyl groups. 5 Such color components have the character of anionic wetting agents. High molecular weight plasticizers with cationic groups consequently lead to coagulation.

The object of the present invention is to provide plasticizers for gelatine-containing photographic layers, which plasticizers are not washed out of the layer and do not deleteriously affect the photographic properties of the layer.

We now have found that water-insoluble amides, urethanes and carbonates of the following formula are excellently suitable as plasticizers for gelatine compositions, especially photographic gelatine layers:

- R2 0 l RiZ-O(CH)D X wherein:

X represents a group of the formula OR or Rs -N \R4 R represents straight-chained or branched alkyl radical having 4 to 18 carbon atoms, preferably with 4 to 12 carbon atoms;

Z stands for a simple chemical bond or a phenylene group, which can be substituted, e.g. with halogen such as chlorine or bromine, alkyl or alkoxy having preferably up to 6 carbon atoms;

R represents hydrogen or alkyl having up to 4 carbon atoms;

R represents a saturated or unsaturated aliphatic group with up to 18 carbon atoms, cycloalkyl such as cyclohexyl, aryl, in particular a radical of the phenyl series, which can be substituted as indicated in respect of Z, or a group of the formula x represents a number from 2 to 6;

R represents hydrogen, a saturated or unsaturated aliphatic group with up to 18 carbon atoms, whereby, however, R and R together must not have more than 20 carbon atoms, cycloalkyl, such as cyclohexyl, or aryl in particular a radical of the phenyl series, which can be substituted as indicated in respect of Z; and

n represents 0 or 1.

The plasticizers according to the invention are insoluble in water. They are preferably added to the gelatine layers in the form of an aqueous dispersion. In general, the procedure can be as follows:

The compounds according to the invention are dissolved in a solvent which is only partially miscible with water and the solution is dispersed in a gelatine solution which contains suitable wetting agents. The dispersion which is thus prepared and which can contain 0.05 to 1, or up to approximately two parts by weight of the compound according to the invention per part by Weight of dry gelatine, serves as a stock solution. 6 to 60% by weight of the compounds according to the invention, calculated on gelatine are added to the casting solution of the photographic gelatine layer, for example, a silver halide gelatine emulsion. With higher contents of plasticizer, the compounds according to the invention can also be directly dispersed in the silver halide gelatine emulsion. Generally speaking, however, a very good plasticizing effect on the gelatine is already obtained from a by weight addition. Suitable wetting agents for the dispersion are, for example, dialkyl naphthalene-sulfonic acids, and cane sugar esters of fatty acids.

The layers plasticized or softened by an addition of the compounds according to the invention can contain other high molecular weight, water-soluble and water-insoluble compounds, such as polyvinyl pyrrolidone, polyvinyl methyl ether and polyvinyl alcohol, acrylic acid as homopolymers or copolymers thereof with derivatives thereof such as acrylates, polystyrene-sulfonic acid, polyvinylsulfonic acid, and also natural substances, such as gum arabic, dextrans, levans and other soluble polysaccharides. Water-insoluble compounds and also Water-insoluble synthetic plastics compatible with gelatine, latices of polyacrylates and mixed polymers thereof, polyvinyl ethers and the mixed polymers thereof can likewise be added.

The compounds according to the invention are capable of being used in identical manner in silver halide emulsion layers or in photographic auxiliary layers, such as protective and intermediate layers. They are particularly compatible with Water-soluble difiusion-resistant color couplers. The compounds according to the invention do not exude and do not reduce the adhesion to the support or to other layers.

The layers plasticized according to the invention are less brittle than comparison layers without the additive. When the compounds are used in a top layer (protective layer), the surface slipping capacity and the resistance to scratching are increased. The photographic properties are practically unchanged. Fogging and decrease in sensitivity do not occur. No additional defects arise during storage in a heating chamber. The compounds according to the invention can be used for photographic gelatine layers on any support including transparent supports. The conventional additives, such as hardeners, wetting agents, optical or chemical sensitizers, development accelerators and additives for increasing the silver covering power do not have to be changed.

EXAMPLE 1 Preparation of the dispersion of the plasticizer 13.2 g. of each of the compound as indicated below are dissolved in 50 cc. portions of ethyl acetate and each resulting solution is dispersed in a mixture of cc. of a 6% by weight aqueous solution of gelatine and 10 ml. of a 5% by weight aqueous solution of sodium dibutyl naphthalene sulfonate with a high-speed stirrer for 3 minutes and thereafter treated in a high-power dispersing appliance, such, as a, colloid mill. The ethyl acetate is evaporated in a rotating vacuum evaporator. The mixture obtained can be directly added to the emulsions.

In each instance, to 1 kg. of a silver chlorobromide emulsion which is ready for casting and which contains about 615 g. of gelatine, thereare added 20 g. of the following compounds in the form of the aqueous, gelatinecontaining dispersion:

Experiment lzConipound 1 Experiment 21Compound 2 Experiment 3 :Compound 4 Experiment 4:Compound 6 Experiment 5:Compound 12 Experiment 6:Compound 18 Experiment 7:Compound 22 After the addition, the mixture is thoroughly stirred. The additional casting additives, such as 6.5 ml. of a 3% by weight aqueous formalin solution as hardener and 20 mli of a 10% by weight aqueous sappnin solution as wetting agent are thereafter introduced.

The casting solutions are each applied onto a support of triacetyl cellulose provided with a subbing layer and dried. I

The film specimens which are obtained are irr each instance exposed and:;deve1oped before and after being stored for 3 days irna heating chamber at 60 C. The developer bath has the composition:

1 g. of p-methylaminophenol 13 g. of anhydrous sodium sulfite 1.8 g. of hydroquinone g. of anhydrous soda 1.6 g. of potassium bromide Water to 1 liter.

The development time is 11 minutes.

After being fixed in an acid fixing bath and rinsed for 25 minutes, the specimens are dried. The films obtained do not show any fogging and have the same sensitivity as a comparison film processed in the same manner but without the plasticising additive. The films do not curl, the adhesion to the support is good and the fixed specimens are clear and not opaque.

EXAMPLE 2 To separate portions of a mixture of 1 liter of a photographic emulsion containing 35 'g. of silver halide and 80 g. of gelatine, there are added in each instance, calculated on the gelatine, 30% by weight of the compounds 2, 4, 6, 7, 10 -l2fand 18-;22 while stirring vigorously. Thereafter, 24 g. of 1-hydroxy-4-sulfo-2-naphthoic acid hexadecylamide are added as color coupler. After addition of the conventional casting additives, such as 25 ml. of a 3% by weight aqueous solution of N,N',N"-tris-acryloylhydrotriazine-1,3,5'as hardener and 12 ml. of a 10% by weight aqueous saponin splution as wetting agent, the separate mixture are applied onto a support of cellulose triacetate provided with a subbing layer and the layers obtained are dried at room temperature. The thickness of the layers is uniformly 18a. 1

The films are processed in accordance with the color processing for negative cine film in accordance with FIAT Final Report 943, page 85. Test strips with a width of 1.5 cm. and a length of 30 cm. are stamped out, and these strips are each alternatively subjected to a conditioned air of 35% and 50% relative air humidity at 22 C.

The test for'the brittleness is effected under the climatic conditions as indicated. The film strips are pulled, with the layer side outwards, over two ball-mounted guide rollers (diameter 5 mm.), which bend the film at a distance of 1.5 cm. twice at right angles. The film is tensioned by a 1 kg. weight and is pulled by an eccentric arrangement periodically over the two guide rollers. With each stroke, the film is subjected to strong mechanical stress and breaks after a certain number of strokes. This number is determined automatically and provides a value for the mechanical quality of a film. The highenthe value which is reached, the better is the mechanical duality of the film, The values listed are average values from seyeral measurements. On reaching the value 1500, the measurement is stopped, as only films with outstanding elasticity reach value. Moreover, the brittleness of the supports participates to a strong degree in the measurement at values above 1500. The result of the measurement is to be seen from the following table:

TABLE "N umber of strokes at 35% relative 50% relative Additive air humidity air humidity 0% control 'I 60 30% compound 2. 700 1, 500 30% compound 4- 760 1, 500 30% compound 6 750 1, 500 30% compound 7 750 7 1, 500 30% compound 10: e 700 u 1, 200 30% compound 11 650 1, 100 30% compound 12 450 1, 200 30% compound 18. 1, 500 1, 500 30% compound 19- 1, 500 1, 500 30% compound 20- 750 1, 500 30% compound 21 450 1, 500 30% compound 22 750 1, 500

All additives reduce the brittleness of the layers. The brittleness of the layers without additive is particularly high, as can be seen from the above table.

The layers are clear and do not show any oily deposits on the surface. The photographic samples, when developed, do not show any disadvantages, such as reduction in sensitivity or fogging.

EXAMPLE 3 Preparation of a concentrated plasticiZer-gelatine dispersion A solution of:

1 kg. of a compound according to the invention and g. of an ionic or nori-ionic wetting agent, such as sulfosuccinic abid-bis-(Z-ethyD-hexyl ester, dissolved in a mixture of 1 kg. of methanol and 1 kg of methylene chloride,

is incorporated at 50 C. with vigorous stirring into a solution of:

10 liters of 10% aqueous geiatine and 0.5 liter of'10% aqueous saponin solution.

The dispersion is made, for example, by using a socalled mixing siren, in such a way that the plasticiz'er solution is introduced through a tube close to the rotor of the siren, The solidified emulsion'can be stored without change in a refrigerator and can be added to any casting solution for any photographic gelatine layer.

Preparation of various photographic'layers (a) 1 kg. of a photographic silver chlorobromide emulsion with a gelatine concentration of 8% by weight, which contains 3- (p-stearoylamino-benzoylacetamino -isophthalic acid as yellow coupler, is mixed With 500 g. of the previously described stock emulsion 'of the plasticizer.

(b) :l kg. of a photographic silver bromide emulsion with a content of 5 mol percent of silver iodide with a gelatine concentration of 8% by weight, which contains 1 (3' sulfo 4' phenoxyphenyl)-3-heptadecyl-pyrazol- 5-one as magenta coupler, is mixed with 500 g. of the previously described stock emulsion of the plasticizer.

(c) 1 kg. of the photographic emulsion described under (:b), containing l-hydroxy-4-sulfo-2-naphthoic acid-octadecylamide as cyan coupler instead of the magenta coupler is mixed with 500 g. of the previously described stock emulsion of the plasticizer.

(d) 1 kg. of an 8% by weight casting solution for a gelatine protective layer is mixed with 500 g. of the previously described stock emulsion of the plasticizer.

(e) 1 kg. of a photographic gelatino-silver chlorobromide emulsion with a gelatine concentration of 8% by weight is mixed with 500 g. of the previously described stock emulsion of the plasticizer. I

(f) 0.75 kg. of a 10% by weight aqueous gelatine solution is mixed with 0.75 kg. of the previously described stock emulsion and thereafter 1 kg. of a 50% by weight aqueous baryta paste is incorporated by stirring. The supports.

The above casting solutions (a) to (f) are applied to paper supports and the layers are dried.

Layers with considerably reduced brittleness are obtained. This effect is particularly pronounced in air of low relative humidity. The photographic properties as sensitivity, fogging, gamma-value and color formation, are not changed by adding the compounds according to the invention.

The brittleness of photographic papers is determined by the following method, since the measuring method according to Example 2 cannot be used because of the nonelasticity of the support with photographic papers. After completing processing, specimens with a width of 8.9 cm, and a length of 30 cm. are freed with a sponge from excess moisture and placed on a drying drum transversely of the running direction. The drying takes place at 90 C. in 6 minutes. Unprocessed specimens are also caused to run through the drying drum in the same manner. Immediately after the discharge of the specimens, they are drawn over rollers of different diameters (60 mm. to 10 mm.). About seconds elapse between the ejection and the completion of the test, so that it is not possible for the specimens to become adapted to the humidity of the air in the room. The diameter of the roller in mm. at which the paper breaks is the brittleness value. The flexibility of a layer, and thus the plasticizer effect of a substance, is better the smaller the diameter. A processed black sheet and also the unprocessed material are tested.

The results will be seen from the following table:

Unprocessed, Processed Additive mm. mm.

Without additive (control) 60 50 Compound 21 25 30 Compound 23 35 40 Compound 19 25 30 Compound 24- 25 30 Compound 25 25 30 Compound 26- 25 20 Compound 27 X represents a group having the formula OR or wherein x is an integer from 2 to 6;

R represents hydrogen, a saturated or unsaturated aliphatic group with up to 18 carbon atoms, the total number of carbon atoms in the radicals R and R being no more than 20, cyclohexyl or a radical of the phenyl series; and

n represents 0 or 1.

2. The composition of claim 1, wherein the waterinsoluble plasticizer is a urethane of the formula 3. The composition of claim 1 wherein the waterinsoluble plasticizer is a carbonate of the formula 4. The composition of claim 1, wherein the waterinsoluble plasticizer is a diurethane of the formula 5. The composition of claim 1, wherein the waterinsoluble plasticizer is an amide of the formula 6. The composition of claim 1, wherein the plasticizer is containing in a quantity of 0.05 to 1 part by weight per part by weight of gelatine.

7. The composition of claim 1, wherein the layer is a silver halide gelatine layer.

8. The composition of claim 7, wherein the silver halide gelatine layer contains a dissolved water-soluble, diffusion-resisting, color coupler.

9. The composition of claim 1, wherein the layer is a protective layer.

References Cited UNITED STATES PATENTS 3,374,095 3/ 1968 Dieterich 961 14.4

FOREIGN PATENTS 1,114,721 France 96-1 1 .4

1,530,045 France 96114.4

NORMAN G. TORCHIN, Primary Examiner M. F. KELLEY, Assistant Examiner 

